“Arm-first” approach for the synthesis of star-shaped stereoregular polymers through living coordination polymerization

Abstract

The synthesis of stereoregular star polymers, including star cis-1,4-PB, star cis-1,4-PB-ran-3,4-PI and star cis-1,4-PB-b-syn-PS, through an “arm-first” approach via a living coordination polymerization mechanism is reported in this work for the first time. The half-sandwich scandium catalyst (C₅Me₄SiMe₃)Sc(CH₂SiMe₃)₂(THF) activated with [Ph₃C][B(C₆F₅)₄] is used herein. Star cis-1,4-PB compounds with various arm lengths and arm numbers ranging from 1.0 × 10⁴ to 6.5 × 10⁴ g mol⁻¹ and 7.6 to 26.4, respectively, are produced by tuning the polymerization parameters. Additionally, the stereoregular star cis-1,4-PB-ran-3,4-PI and star cis-1,4-PB-b-syn-PS are also explored in the same way with average arm numbers of 21.4 and 16.5 and 35% and 41% star yield, respectively.